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Homework Help: Time to charge a capacitor- please help

  1. Jul 18, 2010 #1
    1. The problem statement, all variables and given/known data

    Please see the attachment
    ok I am really not very good with this stuff at the moment. From reading the text I have gotten somewhere but have obviously screwed it up. ln -.3 doesn't exist obviously. Please help me with this. thanks

    2. Relevant equations

    3. The attempt at a solution
    attempt can be seen in the same attachment as question. again I really need help with this..

    Attached Files:

  2. jcsd
  3. Jul 18, 2010 #2


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    Homework Helper

    You have on the left side near to the end

    0.7-1 = -e t

    0.7-1 is -0.3

    so you will end up with something like -0.3=-et. The -1s cancel.
  4. Jul 18, 2010 #3
    oh ok thanks - is this the right procedure???
  5. Jul 18, 2010 #4


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    Homework Helper

    Yes it should be.
  6. Jul 18, 2010 #5
    thanks - do you know whats going on with my other problem that we had different answers to????
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